The metabolism, disposition, and excretion of two halogenated alkyl phosphate fire-retardants have been studied in the male rat. Each of these compounds, tris (2,3-dibromopropyl) phosphate (Tris) and tris (1,3-dichloroisopropyl) phosphate (Fyrol FR-2), are rapidly absorbed, metabolized and excreted. The major metabolites are the products of dealkylation reactions which are mediated by both microsomal and soluble enzymes. Excretion is in the urine, feces and as exhaled CO2. There is some evidence that more Tris than Fyrol is covalently bound to the DNA of kidney when animals are exposed to similar doses in vivo.